This invention relates to dynamoelectric machines and more particularly to a sleeve for retaining the conductors disposed longitudinally on the outer surface of the rotor of the dynamoelectric machine.
Dynamoelectric machines normally have a stator and a rotor rotatably disposed within the stator. The rotor has windings disposed in slots longitudinally disposed along the rotor. The winding comprises a plurality of conductors disposed in the rotor and end turns which electrically connect the ends of the conductors to one another.
The windings are held in place against centrifugal force produced as the rotor revolves by two separate systems; the portion of the windings in the slots is retained therein by wedges which are dovetailed into the slots, (see U.S. Pat. No. 3,697,761 by Kilgore at al. and U.S. Pat. No. 3,898,491 by Long et al.); the end turns are retained by a ring which is shrunk on the end of the rotor and covers the end turns, (see U.S. Pat. No. 2,712,085 and 2,773,210). A problem with this system is the rotor winding does not have a continuous support which offers uniform stiffness over the entire winding, that is, the deflection of the ring which retains the end turns is different than the deflection of the rotor body and wedges which retain the straight portion of the winding. Because of the differential deflection, stresses are induced in the winding at the juncture of the straight portion and the end turns. To keep these stresses within allowable limits it is necessary to fabricate the winding utilizing multiple layers of copper strips. The relatively thin strips deflect easily keeping the bending stresses within allowable limits. If the differential deflection were reduced, a single integral conductor could be utilized reducing the cost of the dynamoelectric machine.
As generators become larger, it is desirable to pass more current through the rotor winding; the size of the conductor being limited by slot configuration and layout rather than the cross section of the conductor forming the winding.
If the slots are generally eliminated, more space is available for the conductors and cooling fluid. The rotor may also be formed from smaller forgings, which advantageously reduce the cost of the forgings, improve their soundness, and enhance the quality of their inspection.
Utilizing more conductors, more closely spaced would also result in reduced excitation current.